hibernate-resume-generator: add a generator for instantiating the resume unit.

hibernate-resume-generator understands resume= kernel command line parameter
and instantiates the systemd-resume@.service accordingly if it is passed.

This enables resume from hibernation using device specified on the kernel
command line, and it may be specified either as "/dev/disk/by-foo/bar"
or "FOO=bar", not only "/dev/sdXY" which is understood by the in-kernel
implementation.

So now resume= is brought on par with root= in terms of possible ways to
specify a device.

.gitignore

@@ -76,6 +76,7 @@
 /systemd-gnome-ask-password-agent
 /systemd-gpt-auto-generator
 /systemd-hibernate-resume
+/systemd-hibernate-resume-generator
 /systemd-hostnamed
 /systemd-inhibit
 /systemd-initctl

Makefile-man.am

@@ -70,6 +70,7 @@ MANPAGES += \
 	man/systemd-getty-generator.8 \
 	man/systemd-gpt-auto-generator.8 \
 	man/systemd-halt.service.8 \
+	man/systemd-hibernate-resume-generator.8 \
 	man/systemd-hibernate-resume@.service.8 \
 	man/systemd-inhibit.1 \
 	man/systemd-initctl.service.8 \
@@ -1625,6 +1626,7 @@ EXTRA_DIST += \
 	man/systemd-getty-generator.xml \
 	man/systemd-gpt-auto-generator.xml \
 	man/systemd-halt.service.xml \
+	man/systemd-hibernate-resume-generator.xml \
 	man/systemd-hibernate-resume@.service.xml \
 	man/systemd-hostnamed.service.xml \
 	man/systemd-inhibit.xml \

Makefile.am

@@ -385,7 +385,8 @@ systemgenerator_PROGRAMS = \
 	systemd-getty-generator \
 	systemd-fstab-generator \
 	systemd-system-update-generator \
-	systemd-debug-generator
+	systemd-debug-generator \
+	systemd-hibernate-resume-generator
 
 dist_bashcompletion_DATA = \
 	shell-completion/bash/busctl \
@@ -2146,6 +2147,14 @@ systemd_system_update_generator_LDADD = \
 	libsystemd-label.la \
 	libsystemd-shared.la
 
+# ------------------------------------------------------------------------------
+systemd_hibernate_resume_generator_SOURCES = \
+	src/resume-generator/resume-generator.c
+
+systemd_hibernate_resume_generator_LDADD = \
+	libsystemd-label.la \
+	libsystemd-shared.la
+
 if ENABLE_EFI
 # ------------------------------------------------------------------------------
 systemgenerator_PROGRAMS +=  \

man/kernel-command-line.xml

@@ -351,6 +351,17 @@
                                 </listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>resume=</varname></term>
+
+                                <listitem>
+                                        <para>Enables resume from hibernation
+                                        using the specified device.
+                                        All <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
+                                        pathes are supported. For details, see
+                                        <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+                                </listitem>
+                        </varlistentry>
                 </variablelist>
 
         </refsect1>
@@ -373,7 +384,8 @@
                           <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-                          <citerefentry><refentrytitle>systemd-rfkill@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                          <citerefentry><refentrytitle>systemd-rfkill@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+                          <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                   </para>
         </refsect1>
 

man/systemd-hibernate-resume-generator.xml

@@ -0,0 +1,93 @@
+<?xml version="1.0"?>
+<!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!--
+  This file is part of systemd.
+
+  Copyright 2014 Ivan Shapovalov
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+<refentry id="systemd-hibernate-resume-generator">
+
+        <refentryinfo>
+                <title>systemd-hibernate-resume-generator</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Ivan</firstname>
+                                <surname>Shapovalov</surname>
+                                <email>intelfx100@gmail.com</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>systemd-hibernate-resume-generator</refentrytitle>
+                <manvolnum>8</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>systemd-hibernate-resume-generator</refname>
+                <refpurpose>Unit generator for resume= kernel parameter</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <para><filename>/usr/lib/systemd/system-generators/systemd-hibernate-resume-generator</filename></para>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para><filename>systemd-hibernate-resume-generator</filename> is
+                a generator that instantiates
+                <citerefentry><refentrytitle>systemd-hibernate-resume@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                unit according to the value of <option>resume=</option>
+                parameter specified on the kernel command line.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Kernel Command Line</title>
+
+                <para><filename>systemd-hibernate-resume-generator</filename> understands
+                the following kernel command line parameters:</para>
+
+                <variablelist class='kernel-commandline-options'>
+
+                        <varlistentry>
+                                <term><varname>resume=</varname></term>
+
+                                <listitem><para>Takes a path to the resume
+                                device. Both persistent block device pathes like
+                                <filename>/dev/disk/by-foo/bar</filename> and
+                                <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-style
+                                specifiers like <literal>FOO=bar</literal>
+                                are supported.</para></listitem>
+                        </varlistentry>
+
+                </variablelist>
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+                <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd-hibernate-resume@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>

src/resume-generator/Makefile

@@ -0,0 +1 @@
+../Makefile

src/resume-generator/resume-generator.c

@@ -0,0 +1,95 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Ivan Shapovalov
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdio.h>
+#include <errno.h>
+
+#include "log.h"
+#include "util.h"
+#include "special.h"
+#include "mkdir.h"
+#include "unit-name.h"
+
+static const char *arg_dest = "/tmp";
+static char *arg_resume_dev = NULL;
+
+static int parse_proc_cmdline_item(const char *key, const char *value) {
+        if (streq(key, "resume") && value) {
+                free(arg_resume_dev);
+                arg_resume_dev = fstab_node_to_udev_node(value);
+                if (!arg_resume_dev)
+                        return log_oom();
+        }
+
+        return 0;
+}
+
+static int process_resume(void) {
+        _cleanup_free_ char *name = NULL, *lnk = NULL;
+
+        name = unit_name_from_path_instance("systemd-hibernate-resume", arg_resume_dev, ".service");
+        if (!name)
+                return log_oom();
+
+        lnk = strjoin(arg_dest, "/" SPECIAL_SYSINIT_TARGET ".wants/", name, NULL);
+        if (!lnk)
+                return log_oom();
+
+        mkdir_parents_label(lnk, 0755);
+        if (symlink(SYSTEM_DATA_UNIT_PATH "/systemd-hibernate-resume@.service", lnk) < 0) {
+                log_error("Failed to create symlink %s: %m", lnk);
+                return -errno;
+        }
+
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        int r = 0;
+
+        if (argc > 1 && argc != 4) {
+                log_error("This program takes three or no arguments.");
+                return EXIT_FAILURE;
+        }
+
+        if (argc > 1)
+                arg_dest = argv[1];
+
+        log_set_target(LOG_TARGET_SAFE);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        /* Don't even consider resuming outside of initramfs. */
+        if (!in_initrd())
+                return EXIT_SUCCESS;
+
+        if (parse_proc_cmdline(parse_proc_cmdline_item) < 0)
+                return EXIT_FAILURE;
+
+        if (arg_resume_dev != NULL)
+                r = process_resume();
+
+        free(arg_resume_dev);
+
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}